How in the world would database know which Oracle products you have installed?????

For example, how would it know if you have SQL*Plus installed or not? Or ODBC driver? Or Forms? Or ......

When you run universal installer, have you ever noticed that it asks for any database password if you want to install new product? I guess not. So how would the system be able to record installed products into the database (into which database???) if it doesn't connect to the database?